fig_*.dat contains two rows. Row 1 contains the x-position and row 2 contains the y-position. Each column corresponds to one point particle. For example if fig_0.2.dat has the following form
[[1,2,3,4,5],         
 [2,3,4,5,6]]
this corresponds to
[[x1,x2,x3,x4,x5],
 [y1,y2,y3,y4,y5]]

Each row of point_*.dat gives information at a specific time point. For example if point_b.dat and point_pos.dat both take the following form
[[1,2,3,4,5,6,7,8,9],       -> at time t0
 [2,3,4,5,6,7,8,9,1],       -> at time t1
 [3,4,5,6,7,8,9,1,2]]       -> at time t2
For the first row pos[t0] = [1,2,3,4,5,6,7,8,9] and B[t0]=[1,2,3,4,5,6,7,8,9], this means 
           for pos: [[1,2,3],[4,5,6],[7,8,9]]   ->    [[  x1,  y1,  z1],[  x2,  y2,  z2],[  x3,  y3,  z3]]
           for B    : [[1,2,3],[4,5,6],[7,8,9]]   ->    [[Bx1,By1,Bz1],[Bx2,By2,Bz2],[Bx3,By3,Bz3]]
Therefore, each position in 3D space is connected to a 3D magnetic and electric field, and velocity.